Abstract:
The detection of g-mode pulsations in accreting white dwarfs (WDs) in cataclysmic variables (CVs) with a
large range of effective temperatures ( ) has shown these WDs to be a more diverse class than their isolated Teff
counterparts, the ZZ Ceti and DB pulsators. The simplest contrast of CV to isolated pulsators is an envelope of
solar-like composition (of various helium enrichments if the donor is evolved) rather than pristine hydrogen or
helium. A range of WD masses is expected, from low-mass He core WDs to massive WDs. We investigate the
impact of this diversity on the range of for which T g-modes are unstable. Motivated by earlier theoretical eff
studies, we compare a fiducial g-mode period to the thermal time at the base of the convection zones created by
H and first He (H/He i) ionization or second He (He ii) ionization zones. We find that (for solar composition
envelopes), relative to a fiducial WD mass , the blue edge for a He core WD shifts downward 0.6 M, , 0.4 M
by ≈1000 K, while that for a massive ≈1.2 M, WD shifts upward by ≈2000 K. Surprisingly, increasing Y by
only 10% relative to solar creates an “intermediate” instability strip near . 15,000 K
